Method of coating electrical conductors



Uct. 18,1932. K. M. WATSON METHOD OF COATING ELECTRICAL CONDUCTORS FiledAug. 30, 1930 //1venf0r K M Watson w/ q y Patented a. 1a, 1932 UNITEDSTATES PATENT OFFICE KENNETH M. WATSON, OI CHICAGO, ILLINOIS, ASSIGNORTO WESTERN ELECTRIC COE- PANY, INCORPORATED, OF NEW YORK, N. Y., A.CORPORATION OF NEW YORK METHOD OI COATING ELECTRICAL CONDUCTORS Driginalapplication filed December 16, 1926, Serial No. 155,808. Divided andthis application filed August 30, 1930. Serial No. 479,066.

This invention relates to methods of coating electrical conductors, andmore particularly to methods of baking a coating of insulating enamelupon a wire, and is a division of m copendin application Serial No.

led December 16, 1926.

The primary object of this invention is to provide a simple andefiicient method of economically and expeditiously baking a coat- ;ingon electrical conductors.

In order to obtain these and other objects and in accordance with thegeneral features of the invention, one embodiment thereof in anapparatus by means of which the method may be etficiently practicedincludes apparatus for continuously passing a wire through a bath ofinsulating material. The wire prior to its entrance into the insulatingmaterial is passed over a pulley which forms one ter- 20 minal of asource of electrical current supply, and subsequent to this coatingoperation the wire is passed over a rotary member which forms the otherterminal of a source of the electrical current supply. blades carried bythe rotary member penetrate the insulating coating and contact with thewire, thereby including an ever-changing wire portion of constant extentwithin an electrical circuit, the current passing therethrough servingto heat the wire and thereby bake the insulating coating. Restrictedopenings formed in the coating during the penetration of the bladescompletely close due to the normal flow of the insulating coating, thuspresenting a wire coating which is of a uniform and homogeneouscharacter.

These and other objects will be apparent from the following detaileddescription, reference being had to the accompanying drawing in whichFig. 1 is a fragmentary side elevational view, partially in section of awire insulating apparatus, a circuit diagram including a source of lowfrequency current supply being shown in association therewith, and

Fig. 2 is an enlarged fragmentary sectional view of the rotary membertaken on the line 2-2 of Fig. 1.

Referring now to the drawing, wherein 60 like numerals have beenemployed to desig- Sharp edged nate similar parts throughout the variousfigures, it will be observed that a wire supply spool is carried byabracket secured on the side of a suitable machine frame 11. Wire 13from the supply spool 10 passes downwardly over a metallic pulley 14which is mounted upon a bracket 16 secured to the machine frame 11 andelectrically insulated from the bracket by means of an insulatingbushing 17. From the pulley 14 the wire 13 is directed downwardly into abath of insulating material 19 within a suitable container 20 and isguided therethrough by means of a pulley or sheave 21 rotatably'mountedwith-.

in the container. After passing through the bath 19 the wire is directedupwardly through a heating chamber 22 and passes over a pulley or sheave23 which is supported by the upper endof a vertical bracket 24 suitablymounted upon the upper portion of the machine frame 11. The wire is thenfed downwardly from this sheave 23 to a sheave (not shown) companion toand in alignment with the sheave 21 and then upwardly over an idlerguide pulley 25. From the pulley 25 the wire is passed over a rotarymetallic member 26 which is provided with a plurality of sharp edgedblades 27 of electricalvconducting material and then to a receivingspool 29 WlllCll may be driven from any suitable source of power (notshown), the speed of the spool being regulated to the speed at which itis desired to feed the wire upwardly through a heating chamber 22.

The rotary member 26, which is slotted to receive the blades 27 andprovided with peripheral flanges 30 (Fig. 2), is mounted upon a suitablesupport 32 and is electrically insulated therefrom by an insulatingbushing 33. It will be observed that this rotary member 26 and thepulley 14 form opposite terminals of an electrical circuit whichincludes a suitable source of low frequency electrical current supply35, a switch 36, a transformer 37, a swltch 38 and an adjustableresistance 39. The circuit including the secondary winding of thetransformer 37 may be traced in part from a spring brush 42 engagingwith a hub on the pulley 14 through the adjustable resistance 39,through the secondary winding of the transformer 37, the switch 38, andthence to a spring, brush 43 engaging a hub on the rotary member 26. a,Theblades 27, suitably secured within companion slots of the rotarymember 26, extend slightly beyond the periphery thereof and when acoated wire from the sheave 23 passes over the rotary member, the sharpedges of these blades successively penetrate the coatingand contact withthe wire (Fig. 2), thus completing the secondary circuit, abovedescribed, by establishing an electrical connection between the rotarymember 26 and the pulley 14 through the portion of the wire 13 extendingtherebetween. From the foregoing it will be clear that when the switches36 and 38 are closed and the electrical circuit is completed through thewire 13 as described, current will flow therethrough and by properadjustment of the resistance 39, the heat generated thereby within thatportion of the wire may serve to effectively bake the coating ofinsulating enamel previously applied to that portion. In this connectionnit is to be understood that a plurality of tively preclu 40 sheavessimilar to the, sheaves 21 and 23 might be employed, the-number ofsheaves being dependent upon the number of times it is desired to passthe wire through the coating compound and through the chamber 22 beforepassing it over the blades 27. The member 26 is freely rotatable in thesupport 32 so that as the coated wire is drawn over the blades 27, thespeed of travel of the wire and the blades will.be the sameand hence anytendenc .to causea relative movement between t e sharp edges of theblades and the coating through which they penetrate is posied. By thisconstruction the size of openings or incisionsmade in the coatings arekept within desirable restricted I 'hmits.

In some instances it is desirable to control the temperature of the,coated wire 13 as it passes over and is carried into contact with theblades 27. The reason for this will be obvious wthenit is understoodthatas the wire 13 contac s with a blade 27, it is desirable to have theblade and the member 26 in whichv 'it is mounted at substantiallythesame temblade, there might.

transfer of heatfrom the wire to the rotary perature as the wire. Shouldthe wire be at a much higher tem erature than that of the a tendency fora quick I member 26 which would result in a sudden contraction of thewire and hence the possible scraping of the blade thereon. This scra ingmight have a tendency to enlarge t e incision made by the blade, andobviously it is desirable to make the smallest possible incision ineffecting the contact. between 'the blade and the wire. In order torender possi ble this temperature control a pipe 45 having acommunication with a suitable source of water supply (not shown) througha valve 46 is adapted to project a stream of water or other suitablequenching medium upon the coated wire as it approaches the blades 27 andin this manner the temperature of the rotary member 26-and the wire 13may be properly regulated.

By the practice ofthis improved method an electrical heating current maybe passed through successive, ever-changingportions 'of a coated wireof'uniform len h, this length being determined by the extent of wirereaching between the blades 27 and the metallic pulley 14. In thedisclosure a source of low frequency current supply 35 has beenpracticed which renders possible the direct i contact of a terminal (theblades 27) of a source of electrical current supply with a moving coatedwire, one of the blades alwaysbeing in contact with the conductor,thereby eatly facilitatin the baking of the coating 1 y the passage 0 alow frequency current through an ever-changing constantjportion of thewire.

It is to be understood that the invention is not limited'to the exactconstruction and functional characteristics herein described and thatthe appended claims have been drawn to define other modifications which.

come'within the true spirit and scope of the invention.

What is claimed is: 1. The method of insulating an electrical conductor,which consists in coating'the eonductor, and then making a directcontact with the conductor through the coating thereof to connect theconductor with a source of electrical current supply, thereby heatingthe conductor to bake the coating.

The penetrations or incisions 2. The method ofinsulating an electricalconductor, which consists in coatin the conductor, and then passing alow requency electrical current I through ever-changing portions of theconductor of constant extent,

thereby heating the conductor to bake the coating. v 3. The method ofinsulating an electrical conductor, which consists in-coating theconducto'r, directly contacting one terminal of a source of electricalcurrent supply with an uncoated portionof the conductor, and thenpenetrating the coating 'to directly contact the other terminal of thesource of current supply with the; conductor, thereby heating theconductor to bake the coating.

4. The method of insulating an electrical conductor, which consists incoating the conductor, and then connecting the conductor with a sourceof electrical current supply by penetrating the coating and contactingwith the conductor to cause an electrical heating current to passtherethrough and bake the coating. v

5. The method of insulating an electrical conductor,'which consists incoating the con ductor, making a direct contact with the conductorthrough a restricted opening in the coating thereof to connect theconductor with a source of electrical current supply, thereby heatingthe conductor to bake the coating and then closing the restrictedopening in the coating.

6. The method of insulating an electrical conductor, which consists incoating the conductor, connecting the conductor with a source. ofelectrical current supply by penetrating the coating and contacting withthe conductor to cause an electrical heating current to pass through theconductor for baking the coating, and controlling the temperature of theconductor during the contacting of the terminal therewith.

7. The method of insulating an electrical conductor which consists ofmoving a conductor through an insulating icompound, making an electricalcontact therewith prior to the conductor entering the compound, makingelectrical contact with the moving conductor through the insulatingcoating thereon at predetermined spaced successive points from saidfirst contact, and passing an electrical current through said contactsto the .conductor to bake the insulating coating thereon. I

In witness whereof, I hereunto subscribe my name this 22nd day of AugustA. D. 1930.

KENNETH M. WATSON.

